Generally, a transportation container is handled by a special crane. The transportation container is handled in such a manner that a hoisting attachment-laterally moving means in which a hoisting attachment is disposed laterally moves on a body mount, the hoisting attachment is vertically moved by the hoisting attachment-laterally moving means. At that time, to avoid collision between a transportation container which is stacked below the crane and a transportation container which is handled by the hoisting attachment, there is disclosed a technique for measuring a position of the transportation container stacked below the crane (see patent document 1 for example).
The conventional technique for measuring a container position will be described below with reference to a drawing.
FIG. 7 is a diagram showing an entire yard crane having a container collision-preventing apparatus. In FIG. 7, a crane 105 which handles a container 101 includes a laterally moving body 111 which vertically moves a hoisting attachment 110. There is disclosed a method in which a two-dimensional laser sensor 113 having a fan-shaped detection range in a laterally moving direction is mounted on the laterally moving body 111 at its location where a lower edge of the container 101 suspended by the hoisting attachment 110 can be seen, the laterally moving direction is scanned by the two-dimensional laser sensor 113, and position data of the lower edge of the container 101 and a corner portion of a ceiling surface of a container 102 which is to be stacked is measured by the two-dimensional laser sensor 113.    [Patent Document 1] Japanese Patent Application Laid-open No. 2005-104665